There are certain exercises that, when showcased on the 'gram, look totally doable, but in reality, are extremely difficult to execute—even for the super fit among us.

The pistol squat is one example. The single-leg squat, which involves lowering your body almost completely to the floor using the strength of just one leg, while holding the other leg out in front and parallel to the ground, can come across as elegant and almost effortless (see here, here and here). But in reality, it involves a no-joke combo of strength, balance, and mobility.

“Personally, I have a hard time doing pistol squats,” Kira Stokes, NYC-based certified trainer, fitness instructor, and creator of the Stoked Method, whose clients include Fuller House actor Candace Cameron Bure, tells SELF. “It doesn’t feel good on my low back and my hips go out of of alignment.”

Even though it’s not a full-blown pistol squat, “trust, it’s far more challenging than it looks,” Stokes writes in the caption—and there are several reasons for that.

For starters, single-leg skater squats are an amalgamation of several tough moves.

“It’s not a squat, it’s not a lunge, it’s not a deadlift,” says Stokes. “It’s a combination of all three.”

The move involves bringing one leg backward, which mimics the movement of a reverse lunge. But unlike in a reverse lunge, where most of us often put some weight on the ball of the back foot, says Stokes, the back foot stays completely elevated in this move, which requires “a lot more control and focus on hip stabilization and strength,” she explains.

The single-leg skater squats also involve a slight hinging forward of the upper body, say Stokes, and “this hinge reminds people of a deadlift.” Lastly, the positioning at the bottom of the movement when the standing knee is bent and the hips and glutes are pushed back is reminiscent of a squat.

Thanks to this trifecta, this move “hits the quads, glutes, and hamstrings in a balanced way,” Stokes says. It also help build strength and stability in your hips.

What’s more, it’s a single-leg (or unilateral) exercise, which means you’re relying on the strength and power of just one leg to support your entire body.

In addition to helping you identify (and fix) any muscle imbalances you may have from side to side, single-leg exercises like these single-leg skater squats challenge your balance and activate the smaller stabilizer muscles in your core—which play a big role in keeping your body stable throughout movements that test your balance.

These reasons are why “it’s super important for your exercise programming to have unilateral movements,” says Stokes.

This move is also great for those with tight hip flexors.

The move is great if you feel tightness or stress in your hip flexors when performing a move like the pistol squat or single-leg box squat, says Stokes. That’s because these moves involve holding the non-working leg in front of the body, which engages your hip flexors. This can be uncomfortable if they're tight. In Stokes' single-leg skater squats, the non-working leg reaches behind the body, which lengthens the hip flexor instead.

If you spend most of your day sitting, it's likely you have tight hip flexors. Also, Stokes says that from her experience, it's an especially common problem for runners. She recommends runners try the single-leg skater squats because they put less stress on this area, while closely mimicking the motions of running—which essentially is a series of unilateral movements repeated over and over. The move also focuses on glute activation, an important component of running, says Stokes.

Here’s how to do the single-leg skater squats.

Place a pad (or stack of pads), BOSU ball, or stack of towels directly behind you.

Stand with your feet hip-width apart.

Lift your left foot off the floor and bend your knee, transferring the weight into your right leg. Brace your core and maintain a straight back as you hinge at the hips to lean your torso slightly forward. Your arms should be straight and angled slightly back behind your glutes. This is the starting position.

Push your hips and glutes backward and bend both knees to slowly lower yourself down and back, bending at the elbows and bringing your arms forward and together as you descend. Continue lowering until your left knee lightly touches the padding, ball, or towels.

Upon contact, push through the heel of your right leg, squeeze your glutes, and return to the starting position, lowering and straightening your arms as you go. Squeeze your butt as you stand up straight. This is 1 rep.

Do 12 reps; switch legs and do 12 reps with the other leg.

Aim for 4 sets of 12 reps on each leg (24 total reps per set).

As you perform the squats, make sure your hips stay as squared off as possible, says Stokes. Watching yourself in the mirror can help with this, as you’ll clearly see if your hips are sticking out to the side.

Also, when you set your knee down on the padding or ground, keep your foot—and if possible, your shin—elevated. This will keep the strengthening focus on the grounded leg, says Stokes.

To make the move easier, increase the height of the padding behind you to reduce the depth of your squat. If you’re having trouble balancing, grab a pair of light weights and raise them laterally in front of you as you squat. “It sounds counterintuitive, but the weights can actually help make the move easier,” says Stokes. “They help stabilize you and can significantly improve your balance.”

To increase the difficulty of the move, reduce the height of the padding (or remove it entirely) to bring your knee closer to the ground.

“You have to try it to understand it,” says Stokes of the move. “Sometimes the exercises that may not look the most exciting are the ones that we need the most.”